The new SRAM RED Powerdome X is the most advanced cassette ever made. Its super light, deadly silent, & delivers an undeniable performance advantage. The eight cogs in the middle are machined from a single block of high grade tool steel, increasing stiffness while weighing even less than a titanium cassette. Between each cog in the block is a Stealth Ring elastomer to reduce vibration & noise. Cutouts on the rear cog further reduce weight & add stiffness. Its the final piece in the drivetrain puzzle, paired with the new SRAM RED Rear Derailleur, delivers ultra-fast, ultra-quiet shifts that will always put you in the right gear.